Team hopes Lemonier, Skuta and maybe Lynch can fill in for outside linebacker who's looked better than ever this summer, but will likely be suspended soon

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Linebacker Aldon Smith is waiting to find out how much time he will miss in the 2014 season. (Photo by Jeff Gross/Getty Images)

In just three NFL seasons, Aldon Smith has been dominant.

The 49ers’ outside linebacker has 42 regular-season sacks and has been among the league’s most feared pass rushers. And, in recent joint workouts with the Baltimore Ravens, Smith looked as if he might even be better in 2014.

Ravens head coach John Harbaugh made a point to single out Smith as “pretty good” after the sessions, and Baltimore left tackle Eugene Morris was effusive with his praise.

“He really can do it all,” he told Eric Branch of the San Francisco Chronicle. “He’s a guy who can press upfield. A guy who can work the edge if he wants to, but certainly has the quickness to fake you out. Hits the inside moves, too. So obviously you have to be on your toes every play against a guy like that.”

Niners head coach Jim Harbaugh says it appears Smith has taken his game to an even higher level, and San Francisco’s Pro Bowl tackle Joe Staley has told teammates this summer that Smith has been almost unstoppable.

Yet when the season opens with the 49ers in Dallas on Sept. 7, Smith isn’t expected to be on the field. He’s expected to receive a multi-game suspension from the NFL for several off-the-field problems he’s had the past two years.

Yet as much as the 49ers would like to have No. 99 on the field chasing QBs, the team is confident it has some excellent short-term help to fill the void, which could be as long as six or eight games.

Veteran Dan Skuta and second-year pro Corey Lemonier filled in very well for Smith last year when he missed fives games while he was in a rehabilitation facility, and this summer the team also has rookie outside linebacker Aaron Lynch, who’s been one of the most impressive first-year players in camp.

Defensive coordinator Vic Fangio says Lemonier and Skuta both have performed well this summer. Lemonier, who has strong pass-rushing skills, added 10 pounds of muscle in offseason conditioning and says he feels much more confident. Lemonier played on passing downs in 2013, with Skuta getting snaps in the base defense. As a rookie, Lemonier had a sack for a safety, 15 tackles, a forced fumble and two passes batted down.

He says he worked hard this offseason to make himself better. If Smith is out for any length of time, Lemonier will get plenty of opportunities to prove it.

Lynch, meanwhile, is a 276-pound outside linebacker who can move. He’s adapting to outside linebacker in the NFL after playing defensive end at South Florida, after transferring from Notre Dame after one season.

“I am going to fit the scheme I am supposed to fit,” he told Kevin Lynch of the San Francisco Chronicle. “(I’m) dropping into coverage at 270 pounds, really just learning and taking everything in.”

If Skuta, Lemonier and Lynch can combine to play well until Smith returns – which could be about the same time inside linebacker NaVorro Bowman gets back from injury – the Niners’ defense should be in good shape.

Safety Eric Reid told the Washington Post that the 49ers defense has plenty of depth to overcome both the Smith and Bowman absences.

“We have some guys that are very capable of filling in those roles for us,” he said. “I see those guys playing well.”